This invention relates to multi-ratio power transmissions, and more particularly, to such transmissions having a secondary input countershaft for transmitting some of the ratios between the input shaft and the output shaft.
In one prior art transmission structure, gearing dedicated to transferring rotation from the input shaft to the countershaft or secondary input shaft by way of the output shaft incorporates an idler gear member rotatably supported on the output shaft. The transfer gearing mechanism thus constructed utilizes axial space to accomplish the transfer function. The axial space utilized can be more gainfully employed.
In another prior art transmission structure, the idler gear is selectively connectible with the output shaft through a selectively operated friction clutch which also requires additional axial space. This arrangement requires the friction clutch to have an open running condition which reduces the efficiency during operation in the other gear ratios. The space utilized by the friction clutch can be more gainfully employed as will be apparent from the following description of the structure disclosed herein.